The present invention relates generally to a storage system for use in a warehouse. More particularly, the invention relates to a high volume storage carousel.
Conventional high volume storage carousels generally fall into two categories: continuously moving carousels and indexing carousels. Continuously moving carousels include a plurality of storage columns that are suspended on and driven by a conveyor. To avoid interferences between containers being delivered to or retrieved from the carousel and containers stored on adjacent storage columns, the storage columns are oversized by a distance equal to the distance traveled by a storage column during the period of time that it takes to unload or load the storage column. This extra spacing reduces the number of storage columns on a carousel and, therefore, reduces the storage capacity of the carousel. Furthermore, since the storage columns are continuously moving, the retrieval and delivery equipment must be able to operate quickly and are, therefore, typically designed to grab the containers rather than push the containers. To minimize damage to the containers, most continuously moving carousels store the containers in totes, which are grabbed by the retrieval and delivery equipment; these totes, however, restrict the size of the containers that can be stored on the storage carousel. Moreover, the retrieval and delivery equipment tends to be relatively complicated.
In U.S. Pat. No. 4,983,091 to Lichti, Sr. et al., a "toteless" continuously moving storage carousel is disclosed. Like the other continuously moving carousels, the Lichti carousel requires the individual storage columns to be spaced apart a distance equal to the distance traveled by a storage column during a retrieval or delivery cycle. The containers are transferred to the carousel by a shuttle which includes supporting arms. In order to accommodate the supporting arms, the shelves of the storage columns have irregular side edges. These irregular side edges permit the supporting arms of the shuttle to slide under the container and lift the container supported thereon off the shelf without traversing the shelf. However, these irregular side edges and supporting arms tend to restrict the size of the packages that can be stored on the carousel.
On the other hand, indexing carousels include a drive conveyor that stops and starts so that the storage columns can be moved one by one to a delivery or retrieval location where the individual storage columns are stopped for loading with or unloading of containers. While indexing carousels generally provide more storage space than continuously moving carousels, stopping and starting these indexing carousels requires a great amount of energy and exerts a significant strain on the system and the individual parts of the carousel-moving carousels tend to be large, typically weighing up to 90,000 pounds.
Therefore, there is a need for a storage carousel that can provide the increased storage capacity associated with indexing carousels and the advantages of loading or unloading on to a relatively stationary storage rack and yet does not require the expenditure of energy or the increased maintaince associated with indexing carousels.